1. Field of the Invention
This invention relates to a signal transferring device for transmission, or reception, or transmission-reception, of electrical signals between a photographic instrument such as a single lens reflex camera or micro film camera using silver halide film, or a camera using video tape film, or a magnetic recording type camera, and an accessory such as an interchangeable lens or an intermediate tube attached to said photographic instrument.
2. Description of the Prior Art
In the art of photographic systems of mechanisms, taking an example of a single lens reflex camera and an interchangeable lens therefor, upon consideration of a system receptive of control signals from the camera body to control the operation of the individual mechanisms in the interchangeable lens mounting, for example, diaphragm, focusing lens, various filters, shutter and the like, and feasible to transmit electrical signals from all the above-described mechanisms to the camera body, a technical problem arises in the transfer of the electrical signals between the camera body and the interchangeable lens mounting.
The signal transferring device already known in the art has a form that electrical signal contact points or terminals are arranged on either mount surface (portion) of the camera body and the lens mounting so that the attachment of the lens to the camera body is completed, the electrical signal contact points or terminals come into engagement with the corresponding ones on the camera body.
The signal contacts in the device of such form are made either fixedly secured in prescribed positions on the camera housing or the lens casing, or movable as are given respective biasing forces by springs to obtain assurance of sufficient conduction therebetween.
In such conventional device, as the signal contacts are located inside, or on the surface of, the mount, it is in the former case that a problem arises from the large limitation on the availability of space, and in the latter case that when attaching, the contacts are caused to frictionally slide on the confronting surface of the opposite mount over the entire range of rotation of the lens relative to the camera body. This implies that the contacts unavoidably move across the heads of screw fasteners by which the mount ring is fixedly secured to the lens casing, or the camera housing, giving a problem that the tips of the contacts are worn off or contaminated with oil with the result of a loss in the electrical conduction. The maximum possible number of contacts to be provided in the interior of, or on the surface of, the mount is also largely limited.